Preparation method of base film for flexible copper-clad plate

Abstract

The invention discloses a preparation method of a base film for a flexible copper-clad plate, which comprises the following steps: S1, in an ice-water bath, completely dissolving a diamine monomer in a solvent, and then adding dianhydride to react to obtain polyamide acid; s2, adding alicyclic epoxy resin and an adhesion promoter, and fully stirring to obtain a glue solution; s3, coating one surface of a copper plate with the glue solution, and sequentially performing solvent volatilization and imidization to obtain a flexible copper-clad plate containing a base film; the solvent evaporation temperature is set to be 80-200 DEG C; the imidization temperature ranges from 250 DEG C to 350 DEG C. The process is simple, convenient and easy to operate; the base film with good stripping performance, transparency, bending resistance and high temperature resistance is prepared by compounding polyamic acid, alicyclic epoxy resin and an adhesion promoter.

Description

Technical Field

[0001] The invention relates to the technical field of electronic material production, and in particular to a method for preparing a base film for a flexible copper-clad laminate. Background Art

[0002] Flexible copper clad laminate is the basic material for producing flexible printed circuit boards. Flexible printed circuit boards include a copper conductive layer and a polyimide substrate layer. According to the number of layers of the copper conductive layer, the structure of the flexible printed circuit board is divided into single-sided copper board, double-sided copper board and multi-layer copper board composite. In the prior art, the substrate layer is often connected to the conductive layer through an adhesive layer. The resulting flexible printed circuit board has poor high temperature resistance and is prone to delamination, and the process is cumbersome.

[0003] Therefore, it is necessary to improve the substrate layer for flexible copper clad laminate in the prior art. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects in the prior art and provide a method for preparing a base film for a flexible copper clad laminate, which has a simple process and is easy to operate. By compounding polyamic acid with alicyclic epoxy resin and an adhesion promoter, a base film with good peeling performance, transparency, bending resistance and high temperature resistance is obtained.

[0005] In order to achieve the above process effect, the technical solution of the present invention is: a method for preparing a base film for a flexible copper clad laminate, comprising the following steps:

[0006] S1: In an ice water bath, firstly dissolve the diamine monomer completely in a solvent, and then add dianhydride to react to obtain polyamic acid;

[0007] S2: Add alicyclic epoxy resin and adhesion promoter and stir thoroughly to obtain glue solution;

[0008] S3: coating the adhesive on one surface of the copper plate, and sequentially performing solvent volatilization and imidization to obtain a flexible copper-clad laminate containing a base film;

[0009] The solvent evaporation temperature is set to 80-200°C;

[0010] The imidization temperature is 250-350°C.

[0011] Furthermore, the base film has a thickness of 5 to 50 μm. Furthermore, the base film has a thickness of 15 to 30 μm.

[0012] Furthermore, the copper plate has a thickness of 12 to 70 μm.

[0013] Furthermore, the film travel speed during the imidization process is 1 to 2 m / min.

[0014] The preferred technical solution is: based on the total amount of diamine monomer as 100%, the diamine monomer includes 60% to 80% of 4,4'-diaminodiphenyl ether and 10% to 30% of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl and 0% to 10% of toughening diamine monomer. Further, the diamine monomer includes 70% to 80% of 4,4'-diaminodiphenyl ether and 10% to 20% of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl and 0% to 10% of toughening diamine monomer. Further, the diamine monomer includes 75% to 80% of 4,4'-diaminodiphenyl ether and 15% to 20% of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl and 0% to 10% of toughening diamine monomer.

[0015] The preferred technical solution is: based on the total amount of dianhydride monomer as 100%, the dianhydride monomer includes 50% to 90% of cyclobutanetetracarboxylic dianhydride and 10% to 50% of hexafluorodianhydride. Further, the dianhydride monomer includes 70% to 80% of cyclobutanetetracarboxylic dianhydride and 20% to 30% of hexafluorodianhydride. Among the diamine monomers, 4,4'-diaminodiphenyl ether is a flexible diamine monomer, which has a high proportion to adjust the bending resistance of the base film, reduce the conjugation effect of the polymer, and improve the transparency of the base film. Among the dianhydride monomers, cyclobutanetetracarboxylic dianhydride is a rigid dianhydride monomer, in order to adjust the mechanical properties of the base film and improve the transparency of the base film.

[0016] The preferred technical solution is: the molar ratio of the diamine monomer to the dianhydride monomer is (0.95-1.05):1.

[0017] The preferred technical solution is: based on the total weight of the diamine monomer and the dianhydride monomer as 100 parts, the adhesion promoter is 0.5-5 parts, the alicyclic epoxy resin is 5-10 parts, and the solvent is 300-900 parts. Further, based on the total weight of the diamine monomer and the dianhydride monomer as 100 parts, the adhesion promoter is 2-5 parts, the alicyclic epoxy resin is 5-8 parts, and the solvent is 500-800 parts.

[0018] The preferred technical solution is: the adhesion promoter is 3,5-diamino-1,2,4-triazole and / or triazabenzenethiol-based compound.

[0019] The preferred technical solution is: the triazabenzene thiol compound is one or more of 2,4,6-trisulfhydryltriaminebenzene, 2-dibutylamine-4,6-disulfhydryltriaminebenzene, 2,4,6-trisulfhydryltriaminebenzene monosodium salt and 2,4,6-trisulfhydryltriaminebenzene trisodium salt.

[0020] The preferred technical solution is: the alicyclic epoxy resin is one or more of EHPE 3150, EPOLEAD GT401, CELLOXIDE 2021P, CELLOXIDE 2081 of Daicel Industries, Ltd., Huntsman CY179, CY184.

[0021] A preferred technical solution is: the toughening diamine monomer is a helical alicyclic diamine unit or a V-shaped alicyclic diamine unit.

[0022] The preferred technical solution is: the solvent is one or more of N-methylpyrrolidone, dimethylacetamide and N,N-dimethylformamide.

[0023] The advantages and beneficial effects of the present invention are:

[0024] The method for preparing the base film for the flexible copper-clad laminate has simple process and is easy to operate.

[0025] By compounding polyamic acid with alicyclic epoxy resin and adhesion promoter, a base film with good peeling performance, transparency, bending resistance and high temperature resistance is prepared;

[0026] Polyamic acid is not only a film-forming material for the base film, but also plays a role as a curing agent for the alicyclic epoxy resin film. DETAILED DESCRIPTION

[0027] The specific implementation of the present invention is further described below in conjunction with the examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.

[0028] model

[0029] 4,4'-Diaminodiphenyl ether (ODA) was purchased from Shandong Wanda Chemical Co., Ltd.;

[0030] 2,2'-Bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB) was purchased from Changzhou Sunshine Pharmaceutical Co., Ltd.;

[0031] Cyclobutanetetracarboxylic dianhydride (CBDA) was purchased from Tianjin Zotye New Material Technology Co., Ltd.; hexafluorodianhydride (6FDA) was purchased from Changzhou Sunshine Pharmaceutical Co., Ltd.;

[0032] Toughening diamine monomer (9,9-bis(4-aminophenyl)fluorene, FDA) was purchased from Tianjin Zotye New Materials Technology Co., Ltd.;

[0033] The non-alicyclic epoxy resin is Mitsubishi Chemical JER828;

[0034] The adhesion promoter was purchased from Japan Sankyo Chemical Co., Ltd., model TA-16.

[0035] The compositions of the glue solutions of the embodiments and comparative examples are shown in Table 1 below:

[0036]

[0037] The method for preparing a base film for a flexible copper clad laminate comprises the following steps:

[0038] S1: Prepare the glue solution according to Table 1, first completely dissolve the diamine monomer in the solvent in an ice water bath, then add dianhydride to react to obtain polyamic acid;

[0039] S2: Add alicyclic epoxy resin and adhesion promoter and stir thoroughly for more than 5 hours to obtain glue solution;

[0040] S3: Coat the glue on one surface of the copper plate in a slot-die coating mode with a coating speed of 3 m / min. Then, the flexible copper-clad laminate containing a base film is obtained by solvent volatilization and imidization. The solvent volatilization temperatures are set to 90°C, 120°C, 160°C, 160°C, 190°C, and 190°C in sequence; the continuous imidization temperatures are set to 220°C, 260°C, 320°C, 350°C, 350°C, 250°C, and 100°C in sequence, and the film traveling speed is 1 m / min.

[0041] The thickness of the copper plate is 35 μm, and the thickness of the base film is 25 μm.

[0042] Comparative Example 3

[0043] Comparative Example 3 is based on Example 1, except that the continuous imidization temperatures are set to 220°C, 260°C, 320°C, 380°C, 380°C, 250°C, and 100°C in sequence, and the film speed remains unchanged.

[0044] Performance Test:

[0045] 1. Bending resistance: According to the JIS C 6471 (R0.38*4.9N) testing method, the sample is made by exposure, development and etching, and then cut into 5 pieces in MD and TD directions. Select the lower fixture with R=0.38mm, load 500g, clamp the test circuit chuck to the two terminals of the instrument respectively, loosen the folding tension rod knob, start the test, and the sample starts to swing until the sample circuit breaks, the machine automatically stops, and then read the data.

[0046] 2. Tensile strength: Cut 5 specimens in MD and TD directions, 15 mm wide and 210 mm long. Clamp the specimens in MD and TD directions on a universal testing machine with a distance of 10 cm between the upper and lower clamps and a tensile speed of 50.8 mm / min.

[0047] 3. Solder heat resistance: Cut the sample into 5cm*5cm size, immerse it in a 300℃ tin furnace, and observe whether there is bursting and bubbling.

[0048] 4. Peel strength: According to the IPC-TM-650 test method, the sample is attached to the fixture with double-sided tape, and the test is performed at a 90° angle and a speed of 50 mm / min.

[0049] 5. Transparency: The transmittance was measured by UV-Vis spectrophotometry at wavelengths of 400 and 500 nm.

[0050] The performance test results of the embodiments and comparative examples are shown in Table 2 below:

[0051]

[0052]

[0053] Compared with Example 1, the ODA content in the diamine monomers of Examples 2 and 3 is reduced, which has a negative impact on transparency, peel strength and bending resistance. The increased ODA content in the diamine monomers can easily lead to a decrease in the thermal stability of the base film, which cannot withstand an environment above 300°C.

[0054] Compared with Example 1, the CBDA content in the dianhydride monomer of Example 4 and Example 5 is reduced, which has a negative impact on the mechanical properties, peel strength and transparency of the base film. The CBDA content in the dianhydride monomer is increased, which has a negative impact on the bending resistance and heat stability, and cannot withstand an environment exceeding 300°C.

[0055] Compared with Example 1, when the content of diamine monomers is reduced in Examples 6 and 7, there is dianhydride monomer that does not participate in the reaction in the reactant system, which has a negative impact on the mechanical properties and transparency of the base film. When the content of diamine monomers is increased, the molecular weight of the obtained polyamic acid is low, which has a negative impact on the mechanical properties and transparency of the base film.

[0056] Compared with Example 1, Example 8 does not use alicyclic epoxy resin, which has a negative impact on the transparency of the base film.

[0057] Compared with Example 1, the adhesive solution in Comparative Example 1 does not contain an adhesion promoter, which has a negative impact on the peel strength of the base film.

[0058] Compared with Example 1, Comparative Example 2 does not contain alicyclic epoxy resin in the adhesive, which has a negative impact on the peel strength and bending resistance of the base film.

[0059] Compared with Example 1, in Comparative Example 3, the imidization temperature is too high, which will cause yellowing of the base film and have a negative impact on its transparency and peel strength.

[0060] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a base film for a flexible copper-clad laminate, characterized in that: The following steps are involved: S1: In an ice water bath, firstly dissolve the diamine monomer completely in a solvent, and then add dianhydride to react to obtain polyamic acid; S2: Add alicyclic epoxy resin and adhesion promoter and stir thoroughly to obtain glue solution; S3: coating the adhesive on one surface of the copper plate, and sequentially performing solvent volatilization and imidization to obtain a flexible copper-clad laminate containing a base film; The solvent evaporation temperature is set to 80~200℃; The imidization temperature is 250-350°C.

2. The method for preparing a base film for a flexible copper-clad laminate according to claim 1, characterized in that: Based on 100% of the total amount of the diamine monomer, the diamine monomer includes 60% to 80% of 4,4'-diaminodiphenyl ether, 10% to 30% of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl and 0% to 10% of the toughening diamine monomer.

3. The method for preparing a base film for a flexible copper-clad laminate according to claim 1 or 2, characterized in that: Based on 100% of the total amount of the dianhydride monomer, the dianhydride monomer includes 50% to 90% of cyclobutanetetracarboxylic dianhydride and 10% to 50% of hexafluorodianhydride.

4. The method for preparing a base film for a flexible copper-clad laminate according to claim 3, characterized in that: The molar ratio of the diamine monomer to the dianhydride monomer is (0.95-1.05):

1.

5. The method for preparing a base film for a flexible copper-clad laminate according to claim 4, characterized in that: Based on 100 parts by total weight of the diamine monomer and the dianhydride monomer, the adhesion promoter is 0.5 to 5 parts, the alicyclic epoxy resin is 5 to 10 parts, and the solvent is 300 to 900 parts.

6. The method for preparing a base film for a flexible copper-clad laminate according to claim 1 or 5, characterized in that: The adhesion promoter is 3,5-diamino-1,2,4-triazole and / or triazabenzenethiol-based compound.

7. The method for preparing a base film for a flexible copper-clad laminate according to claim 6, characterized in that: The triazabenzenethiol compound is one or more of 2,4,6-trisulfhydryltriaminebenzene, 2-dibutylamine-4,6-disulfhydryltriaminebenzene, 2,4,6-trisulfhydryltriaminebenzene monosodium salt and 2,4,6-trisulfhydryltriaminebenzene trisodium salt.

8. The method for preparing a base film for a flexible copper-clad laminate according to claim 1 or 5, characterized in that: The alicyclic epoxy resin is one or more of EHPE 3150, EPOLEAD GT401, CELLOXIDE 2021P, CELLOXIDE 2081 of Daicel Industries, Ltd., and Huntsman CY179 and CY184.

9. The method for preparing a base film for a flexible copper-clad laminate according to claim 2, characterized in that: The toughening diamine monomer is a helical alicyclic diamine unit or a V-shaped alicyclic diamine unit.

10. The method for preparing a base film for a flexible copper clad laminate according to claim 1, characterized in that: The solvent is one or more of N-methylpyrrolidone, dimethylacetamide and N,N-dimethylformamide.

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